Atmospheric substrate processing apparatus for depositing multiple layers on a substrate

ABSTRACT

A substrate processing apparatus is disclosed. In one embodiment, the apparatus includes a first atmospheric deposition station and a second atmospheric deposition station. The second atmospheric deposition station comprises an atmospheric pressure vapor deposition chamber. A substrate handling system is adapted to transfer substrates between the first and the second atmospheric deposition stations.

BACKGROUND OF THE INVENTION

A typical semiconductor fabrication facility can cost billions ofdollars. In view of the high capital costs associated with building andmaintaining a semiconductor fabrication facility, it would be desirableto decrease the time needed to process semiconductor wafers into chips.By reducing the cycle time for chip production, more chips can beproduced in less time, thus maximizing the use of equipment in afabrication facility.

One time-consuming processing step in a chip manufacturing process isthe evacuation and re-pressurization of load-locks, transfer chambers,and processing chambers. For example, FIG. 1 shows a deposition module120 that can be used to deposit layers on semiconductor substrates. Inoperation, a loadlock chamber 124 in a front end staging area 122 isloaded with cassettes containing semiconductor substrates and is pumpeddown to near vacuum. The front staging area 122 can be connected toanother processing module (not shown).

A transfer chamber 126 adjacent to the staging area 122 is pumped downto vacuum or near vacuum using one or more vacuum pumps (not shown)disposed on the deposition module 120. After vacuum pumping to asufficiently low pressure, the vacuum doors 128 of the transfer chamber126 open so that the transfer chamber 126 and the front end staging area122 are in communication with each other. Movable arms on a substratehandler 127 in the transfer chamber 126 retrieve substrates from theloadlock chamber 124. The substrate handler 127 in the transfer chamber126 then transfers the substrates into the processing regions 618, 620of one of the processing chambers 130.

Once the semiconductor substrates are placed in the processing chambers130, the arms of the substrate handler 127 are withdrawn. The slitvalves 132 to the processing chamber 130 are then closed. Otherprocessing chambers may be loaded with substrates in a similar manner.In each processing chamber 130, layers of material (e.g., cappinglayers) are respectively deposited on the substrates using, for example,a plasma enhanced chemical vapor deposition (PECVD) process. Afterprocessing is finished, the slit valves 132 are opened and the arms ofthe substrate handler 127 retrieve the substrates from the processingregions 618, 620. The substrates are then returned to the loadlockchamber 124. Then, the substrate handler 127 retrieves another pair ofsubstrates from the loadlock chamber 124, and the processing continuesin the same manner.

After all of the substrates in the loadlock chamber 124 are processed,the slit valves 132 to the processing chambers 130 are closed. Thetransfer chamber 126 is then vented to atmosphere pressure using aninert gas (e.g., argon) and the front vacuum doors 128 are opened.Another substrate handler (not shown) can then retrieve the processedsubstrates from the loadlock chamber 124.

A significant amount of time is needed to evacuate and re-pressurize theprocessing chambers, the transfer chamber, and the loadlock chambers inthe substrate processing apparatus. It would be desirable to reduce thetime associated with one or more of these steps to reduce the amount oftime needed to process the substrate. Doing so would increase processingefficiency and would reduce the cycle time associated withmanufacturing, for example, semiconductor chips.

Embodiments of the invention address this and other problems.

SUMMARY OF THE INVENTION

Embodiments of the invention are directed to apparatuses and methods forprocessing substrates.

One embodiment of the invention is directed to an apparatus forprocessing a substrate, the apparatus comprising: (a) a firstatmospheric deposition station; (b) a second atmospheric depositionstation comprising an atmospheric pressure vapor deposition chamber,wherein the first atmospheric deposition station and the secondatmospheric deposition station are coupled together; and (c) a substratehandling system adapted to transfer substrates between the atmosphericdeposition station and the second atmospheric deposition station.

Another embodiment of the invention is directed to an apparatus forprocessing semiconductor substrates, the apparatus comprising: (a) anatmospheric chemical vapor deposition chamber; (b) a plasma systemassociated with the atmospheric chemical vapor deposition chamber; (c) aspin coating chamber coupled to the atmospheric deposition chamber; (d)a curing station coupled to the atmospheric deposition chamber; and (e)a substrate handling system adapted to transfer substrates between theatmospheric deposition chamber, the spin coating chamber, and the curingstation.

Another embodiment of the invention is directed to a method forprocessing a substrate using a substrate processing apparatus, themethod comprising: (a) depositing a first layer on a substrate atatmospheric pressure at a first atmospheric deposition station; (b)transferring the substrate to an atmospheric vapor deposition chamber ata second atmospheric deposition station using a substrate transfersystem; and (c) depositing a second layer on the substrate atatmospheric pressure within the atmospheric vapor deposition chamber atatmospheric pressure.

These and other embodiments of the invention are described in furtherdetail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top view of a deposition module including processchambers.

FIG. 2 shows a top view schematic view of a substrate processingapparatus according to an embodiment of the invention.

FIG. 3 shows a side schematic view of a pancake induction atmosphericpressure chemical vapor deposition reactor.

FIG. 4 shows a side schematic view of a horizontal conductionatmospheric pressure chemical vapor deposition reactor.

FIG. 5 shows a side schematic view of a continuous atmospheric pressurechemical vapor deposition reactor.

FIG. 6 shows side cross-sectional views of layers that can be depositedusing an apparatus according to an embodiment of the invention.

DETAILED DESCRIPTION

Embodiments of the invention are directed to substrate processingapparatuses and methods for processing substrates. In one example, theapparatus comprises a first atmospheric deposition station and a secondatmospheric deposition station. The second atmospheric depositionstation comprises an atmospheric pressure vapor deposition chamber. Anatmospheric pressure vapor deposition process such as an atmosphericpressure chemical vapor deposition (APCVD) process can be performed inthe chamber.

Substrates are transferred between the first and second atmosphericdeposition stations using a substrate handling system. The substratehandling system, or parts of the substrate handling system, may behoused in one or more transfer chambers. In the apparatus, thesubstrates may be directly or indirectly transferred from oneatmospheric deposition station to another atmospheric depositionstation. In a typical indirect transfer of substrates, substrates can beprocessed at an intermediate processing station after being processed ata first atmospheric deposition station, but before being processed at asecond atmospheric deposition station. For example, a spin coatingprocess may be performed at a first atmospheric deposition station, acuring process may be performed at an intermediate processing station,and an APCVD process may be performed at a second atmospheric depositionstation.

In embodiments of the invention, the first atmospheric pressuredeposition station may be directly or indirectly coupled to the secondatmospheric deposition station. For example, the first and the secondatmospheric deposition stations may be indirectly coupled together usingone or more intervening process or transfer stations. The interveningstations may include, for example, process chambers (e.g., curingchambers) or transfer chambers that are disposed between the first andsecond atmospheric deposition stations. Together, the first atmosphericdeposition station, the second atmospheric deposition station, and anyoptional processing or transfer stations may form a cluster tool.

Layers of material may be deposited at the first atmospheric stationusing any suitable process and any suitable process equipment. Forexample, the first atmospheric deposition station can have a liquiddispenser to dispense liquids. In this regard, the first atmosphericdeposition station may include, for example, a spin coater with a spincoating chamber, a spray coater (e.g., an ultrasonic spray coater), aroller coater, or a curtain coater. In some embodiments, the liquiddispenser may have one or more nozzles. The one or more nozzles candispense streams or droplets of liquid (e.g., a spray) on a substrate toform a first layer on the substrate.

The second atmospheric deposition station can comprise an atmosphericpressure vapor deposition chamber. In the chamber, a layer can bedeposited using gas phase reactants. For example, an APCVD process or aplasma enhanced APCVD process may be performed at the second atmosphericdeposition station to deposit a second layer on the substrate. Thedeposited first and second layers may be in direct contact with eachother on the substrate or may be coupled together through one or moreintervening layers.

Embodiments of the invention have a number of advantages. As theapparatus comprises a number of atmospheric deposition stations,processing chambers at these stations need not be evacuated andre-pressurized. The time associated with evacuating and re-pressurizingmany different chambers is eliminated or reduced. As a result,substrates can be processed quickly and efficiently. Also, the apparatusembodiments have fewer vacuum pumps than conventional substrateprocessing apparatuses. For example, in some embodiments, all processingstations in the apparatus can process substrates at atmospheric pressureand no vacuum pumps are present in the apparatus. Reducing the number ofvacuum pumps and other hardware associated with the vacuum pumps reducesthe overall complexity of the apparatus. In addition, by using thesubstrate handling system to transfer substrates between the variousprocessing stations in the apparatus, substrates can be processedcontinuously and automatically. Embodiments of the invention cangenerally provide higher throughout, smaller footprint, and lower coststhan other conventional substrate processing apparatuses.

An example of a substrate processing apparatus according to anembodiment of the invention can be described with reference to FIG. 2.FIG. 2 shows an apparatus including a first process module 101 and asecond process module 210. In this example, the first process module 101and the second process module 210 are coupled together via a curingchamber 116.

When the apparatus processes a substrate, a first layer can be depositedon a substrate at a first atmospheric deposition station in the firstprocess module 101. The substrate is typically a semiconductor substrate(e.g., a silicon wafer) and the first layer may be, for example, asol-gel layer. Other processing stations may process the sol-gel layerinto a porous dielectric layer. A second layer can be deposited on thesubstrate at a second atmospheric deposition station in the secondprocess module 210. The second layer may be, for example, a cappinglayer. The capping layer may be on the substrate and in contact with theporous dielectric layer. Sol-gel layers, porous dielectric layers, andcapping layers are examples of the many layers that may be deposited andformed using embodiments of the invention. These particular layers aredescribed in greater detail below.

In the apparatus example shown in FIG. 2, the first process module 101includes a plurality of processing stations and a transfer chamber 108.Each processing station may include a processing chamber. In thisexample, the first process module 101 includes a cooling stationcomprising a cooling chamber 111, a spin coating station having spincoating chambers 114, a curing station having a curing chamber 116, astripping/annealing station having a stripping/annealing chamber 118,and a silylation station having a silylation chamber 123. Furtherdetails about exemplary process modules and the processing chambers inthe first process module can be found in U.S. patent application Ser.No. 09/502,126, filed Feb. 10, 2000, which is assigned to the sameassignee as the present invention and is herein incorporated byreference in its entirety for all purposes. In the example shown in FIG.2, the various process chambers 111, 114, 116, 118, 123 are arrangedaround the transfer chamber 108. Each process chamber 111, 114, 116,118, 123 is in communication with the interior of the transfer chamber108 through various slits 110, 113, 117, 119, 121.

A substrate handler 112 with arms is present in the transfer chamber108. The arms of the substrate handlers 112 can move in a radialdirection to insert substrates into the various process chambers 111,114, 116, 118, 123 or remove substrates from them. In this example, thesubstrate handler 112 has two arms with independent rotational movement.Alternatively, the two armed substrate handler 112 may have arms thatmove in tandem.

In the apparatus shown in FIG. 2, the spin coating station comprisingthe spin coating chambers 114 may be considered a first atmosphericdeposition station. A spin coating process can be used to deposit aliquid on a substrate at atmospheric pressure in each of the spincoating chambers 114. In a typical spin coating process, a liquid isdispensed onto a substrate and is initially deposited as a puddle orstream over one part of the substrate. During or after liquiddeposition, the substrate spins and centrifugal forces distribute theliquid evenly across the surface of the spinning substrate to form acoating on the substrate. The coated substrate can then be baked orcured in the curing chamber 116. The baking or curing process may alsobe performed at atmospheric pressure. Accordingly, in some embodimentsof the invention, some or all of the stations and chambers in theapparatus may operate at atmospheric pressure.

In other embodiments, the first atmospheric deposition station can havean ultrasonic spray chamber (not shown). An ultrasonic spraying processmay be used to form a layer on a substrate. In an ultrasonic sprayingprocess, an ultrasonic spray nozzle is positioned above the substrateand breaks up the process liquid into a fine mist. The spray nozzle ison an arm that moves from the center to the edge of the wafer, orvice-versa. During spraying, a spray envelope extends over a broad areaof the substrate so that the entire surface of the substrate can becovered with the sprayed liquid. The substrate may or may not be rotatedwhile spraying.

Compared with conventional pressure spray nozzles, ultrasonic nozzlesdeliver a low-velocity spray. For example, in a typical ultrasonic sprayprocess, the spray velocity is approximately {fraction (1/100)}^(th) ofthat produced by an ordinary pressure nozzle so excess spraying isminimized. Minimizing overspraying reduces the amount of liquid that isreleased into the environment and reduces the amount of liquid that iswasted during processing. Also, because overspaying is minimized, theamount of liquid deposited on the backside of the substrate isminimized. This can eliminate the need for, or reduce the timeassociated with, a subsequent back side rinse process. In a back siderinse process, the back surface of a substrate is rinsed of any liquidthat was previously deposited on the front surface of the substrate.

The stripping/annealing chamber 118 is capable of performing one or bothof a non-reactive gas anneal and an oxidizing gas strip of a depositedlayer. An example of a stripping/annealing chamber 118 is the WxZ™chamber that is commercially available from Applied Materials, Inc., ofSanta Clara, Calif. Undesired substances may be removed from a depositedlayer using an annealing or a stripping process. For example, during theformation of a mesoporous oxide layer, surfactants can be removed from acured sol-gel layer by annealing the cured layer and/or exposing thecured layer to an oxidizing atmosphere. A high temperature anneal canalso transform a cured sol-gel layer into a mesoporous oxide layer.

The silylation chamber 123 can be used to perform a silylation process.In a silylation process, a layer on a substrate is exposed to asilylating agent. Examples of silylating agents include tetramethyldisilazane (TMDS), hexamethyl disilazane (HMDS), anddimethylaminotrimethyl silane, and combinations thereof. Duringsilylation, the substrate may be at a temperature of about 25° C. toabout 200° C. Many mesoporous oxide layers, for example, are hydrophilicafter they are formed. Silylating a hydrophilic layer on a substrate canrender the layer hydrophobic. Hydrophobic layers are less likely toretain moisture than hydrophilic layers. As explained in further detailbelow, moisture can affect the properties of dielectric and conductivelayers in an interconnect structure.

The first process module 101 may also include a front staging area 102coupled to the transfer chamber 108. Substrate handlers 104 are in thefront staging area 102. The substrate handlers 104 can transfersubstrates between substrate cassettes 106 that are coupled to the frontstaging area 102 and the cooling chamber 111. The substrate cassettes106 are adapted to support a plurality of substrates mounted in a spacedvertical arrangement. A substrate rest 103 is disposed between thehandlers 104 to provide a cooling rest for substrates during substrateexchange between the cooling chamber 111 and the cassettes 106.Alternatively, the substrate rest 103 may preheat the substrates forsubsequent processing. The cooling chamber 111 may cool the substratesfor subsequent processing or prior to exiting the apparatus.

The second process module 210 includes one or more atmospheric pressurevapor deposition stations 205 that are coupled together through atransfer chamber 133. Each station 205 includes an atmospheric pressurevapor deposition chamber 202 and an optional remote plasma chamber 201.Each atmospheric pressure vapor deposition station 205 may have one ormore gas distribution assemblies (not shown). The gas distributionassemblies may uniformly distribute process gases onto the substrateswithin the atmospheric pressure vapor deposition chambers 202. Asubstrate handler 127 is in the transfer chamber 133 and insertssubstrates into or retrieves substrates from the atmospheric vapordeposition chambers 202. Having the substrate handler 127 in thetransfer chamber 133 reduces the likelihood that contamination from theoutside environment may deposit on the substrates being handled. Thesubstrate handler 127 may be the same or different than the previouslydescribed substrate handlers.

The atmospheric pressure vapor deposition processes performed in theatmospheric vapor deposition chambers 202 may be non-reactive orreactive. Examples of non-reactive deposition processes includeevaporation and sputtering. In other embodiments, a reactive depositionprocess may be performed in the processing chamber. Examples of reactivedeposition processes include atmospheric pressure chemical vapordeposition (APCVD) processes and plasma enhanced APCVD processes. APCVDprocesses are especially suitable for forming compound layers, i.e.layers of materials formed from at least two different elements such assilicon nitride, silicon oxynitride, silicon dioxide, aluminum oxide,aluminum nitride, titanium oxide, etc.

In an APCVD process, a non-volatile solid layer is formed on a substrateby a surface reaction of gaseous reactants. A typical APCVD processcomprises (1) introducing gaseous reactants and inert carrier gas into areaction chamber, (2) transporting gaseous reactants to the surface ofthe substrate, (3) adsorbing reagent species onto the substrate wherethey undergo migration and film forming reactions, and (4) removinggaseous reaction byproducts and unused reactants from each chamber. TheAPCVD chamber is at or near atmospheric pressure during deposition.

In general, APCVD processes have higher deposition rates than LPCVD (lowpressure chemical vapor deposition) processes. Accordingly, APCVDprocesses can deposit a layer of material on a substrate faster thantypical LPCVD processes. In order to improve the uniformity of thelayers deposited using APCVD processes, the reactant gases in thechamber can be agitated and/or the substrate being processed can bemoved during the deposition process. For example, many APCVD apparatuseshave a moving substrate holder that supports and moves substrates duringthe deposition process.

The substrate can be heated in an APCVD process to drive the reaction atthe surface of the substrate. For faster reaction rates, the substratesare typically heated to temperatures ranging from about 500° C. to ashigh as about 1600° C. Heat is supplied to the substrate in any suitablemanner. For example, heat can be supplied to the substrate by heating asusceptor that supports the substrate. The susceptors can be heated by,for example, resistive or inductive heating.

Process parameters such as the process gas composition, the process gasflowrates, the substrate temperature, and the chamber wall temperaturesmay be adjusted according to the particular layers being deposited. Inthis regard, specific processing recipes can be created for theparticular layers being deposited. The particular recipes can be createdand stored in a computer at the atmospheric deposition station and canbe determined by those of ordinary skill in the art.

Any suitable APCVD reactor can be used in the atmospheric vapordeposition station 205. Examples of APCVD reactors include cold-wallinduction APCVD reactors, pancake induction heated APCVD reactors,continuous conduction heated APCVD reactors, and horizontal conductionheated APCVD reactors. These reactors are well known in the art. Someexamples of suitable APCVD reactors are shown in FIGS. 3 and 4.

FIG. 3 shows an example of a pancake induction heated APCVD system. Inthe illustrated APCVD system, semiconductor substrates 307 are on arotating holder 308 of graphite. Both the substrates 307 and therotating holder 308 are present within an APCVD chamber 303. Thegraphite holder 308 is heated by induction using an RF coil (not shown)below the holder 308. Reaction gases 309 are fed through a tube 305under the holder 308 and exit the holder 308 above the substrates 307.The holder 308 rotates and the reactant gases 309 react at the surfaceof the substrates 307 to form layers of material.

In a pancake induction heated APCVD system, the reactant gases flowvertically with respect to the substrate. Vertical gas flow offers theadvantage of a continuous supply of fresh reactants to the wafers, thusminimizing downstream depletion. The combination of the substraterotation and the vertical flow of the gases produces good uniformity inthe deposited layer.

FIG. 4 shows an example of a horizontal conduction heated APCVD system.In this embodiment, gases 317 are mixed outside of the chamber 323 andthe mixed gases 317 pass to a showerhead 315. The showerhead 315distributes the gases 317 on the substrates 320. As this distributionoccurs, a hot plate holder 313 moves back and forth under the showerhead315. The gases 317 react at the surfaces of the substrates 320 to formlayers of material on the substrates 320.

In some embodiments, the APCVD process is a plasma enhanced APCVDprocess. In a plasma enhanced APCVD process, energy is applied toreactant gases to form a plasma containing reactive ions. The plasma maybe generated in the deposition chamber or may be generated in a remotechamber. The remote chamber is positioned upstream of the depositionchamber. For example, in the embodiment illustrated in FIG. 2, a plasmais formed in the remote plasma chamber 201 that is upstream of acorresponding deposition chamber 202. The plasma in the remote plasmachamber 201 may be generated using any suitable form of energy. Forexample, RF (radio frequency), RF resonant, microwave, or corona energymay be used to generate a plasma. The formed gaseous ions can passdownstream of the remote plasma chamber 201 and into the atmosphericvapor deposition chamber 202 where they react at the surface of thesubstrate. In general, plasma enhanced processes can deposit layers on asubstrate more quickly and at lower temperatures than non-plasmaenhanced processes.

Any suitable substrate handling system can be used in the apparatus tofacilitate the movement and transfer of the substrates between theprocessing stations and chambers within the apparatus. For example, thesubstrate handling system may comprise any suitable combination of tracksystems, conveyor belts, armed substrate handlers, etc. Such componentsmay operate dependently or independently of each other. For instance, inthe apparatus shown in FIG. 2, the substrate handling system includes afirst substrate handler 112 and a second substrate handler 127. Thefirst and second substrate handlers 112, 127 may work independently ordependently to transfer substrates from the spin coating chambers 114 ofthe first process module 101 to the atmospheric deposition chambers 202of the second process module 210.

In other embodiments, a plurality of different process stations may beseparated from each other by conveyor belts and substrate handlers thattransfer the substrates between adjacent stations. Illustratively, aspin coating chamber, a curing chamber, a stripping/annealing chamber,and an APCVD chamber may form a process line. Substrates can betransferred between adjacent chambers using conveyors and/or substratehandlers that are disposed between the chambers. Substrates can besequentially processed in the spin coating chamber, curing chamber,stripping/annealing chamber, and the APCVD chamber. In these and otherembodiments, a batch of substrates can be substantially continuouslyprocessed without manual intervention.

An example of an APCVD reactor that can be used in a continuous processline is shown in FIG. 5. FIG. 5 shows a reaction chamber 510 thatreceives process gases 507. A noble gas (e.g., argon or nitrogen)“curtain” 505 can be disposed on opposite sides of the reaction chamber510 to confine the process gases 507. Substrates 513 can pass under theprocess gases 510 as they are transported by a conveyor belt 503. Aheater 501 may be under the conveyor belt 503 to heat the substrates 513on a conveyor belt 503 to a suitable process temperature. Using theapparatus shown in FIG. 5, substrates can be processed in a trulycontinuous fashion. For example, substrates can be loaded at one end ofthe reactor and then unloaded at another end of the reactor usingsubstrate handlers. The substrates can be transferred to the reactorfrom a preceding process station and away from the reactor to anothersubsequent process station using conveyors. Thus, one or more otherprocess stations may be coupled to either end of the reactor so thatmore than one layer of material can be deposited on the substrates 513in an automated processing sequence. For example, a spin coating stationor an ultrasonic spray station may be precede and may be coupled to thereactor shown in FIG. 5 to form an apparatus that can deposit multiplelayers on substrates.

As noted, a first layer may be formed on a substrate at the firstatmospheric deposition station and a second layer may be formed on thesubstrate at the second atmospheric deposition station. The first andsecond layers may have any suitable characteristics. For example, eachof the first layer and the second layer may be a dielectric orconductive layer, or a precursor to a dielectric or conductive layer.Either layer may be porous or solid. In addition, if the first or thesecond layer comprises or is formed into a dielectric layer, thedielectric layer may comprise materials such as silicon dioxide, siliconnitride, silicon oxynitride, metal oxides such as titanium oxide, etc.

In some embodiments, the first layer and the second layer may both belayers with dielectric properties. For example, the first layer may be adielectric layer while the second layer may be a dielectric capping orbarrier layer. In other embodiments, the first layer may comprise adielectric material while the second layer comprises a conductivematerial. In yet other embodiments, the first and the second layers mayboth be conductive.

The first and the second layers may also be precursors to a final layeror a final layer in a semiconductor chip. For example, the first layermay be a precursor layer to a porous dielectric layer such as amesoporous oxide layer. The precursor layer may be a sol-gel layer thatis later formed into a dielectric mesoporous oxide layer usingadditional processes such as curing and stripping. The second layer maybe a layer such as a dielectric capping layer that is formed using anatmospheric vapor deposition process. In this example, the dielectricmesoporous oxide layer and the capping layer may be in direct contactwith each other.

Mesoporous oxide layers and capping layers can be used in aninterconnect structure in a semiconductor chip. An exemplaryinterconnect structure 400 is shown in FIG. 6. In FIG. 6, a firstmesoporous oxide 408 is on a substrate 402 that has a pattern ofconducting lines 404. A first capping layer 406 is between the firstdielectric layer 408 and the substrate 402. The first dielectric layer408 may comprise a mesoporous oxide. A second capping layer 410 is onthe first dielectric layer 408 and may have the same or differentcharacteristics as the first capping layer 406. A second dielectriclayer 414 may comprise a mesoporous oxide layer and is disposed over thesecond capping layer 410. A third capping layer 416 is on the seconddielectric layer 408. A conductive via 417 and a barrier layer 420 maypass through the capping layers and the dielectric layers. Theconductive via 417 and the conducting lines 404 may comprise anysuitable conductive material including copper, aluminum, or tungsten. Afourth capping layer 424 may be on the third capping layer 416. Thebarrier layer and the capping layers may comprise any suitable materialincluding, for example, refractory metal nitrides (e.g., tantalumnitride), refractory metals (e.g., tantalum, tungsten), silicon carbides(e.g., amorphous silicon carbide), silicon oxides (e.g., silicondioxide), silicon nitrides, silicon oxynitrides, etc.

Mesoporous oxide layers are desirable as dielectric layers. They have alow dielectric constant and are suitable dielectric barriers betweencopper layers. However, mesoporous oxide layers are highly hydrophilicand are sensitive to moisture contamination. Moisture contamination canalter the dielectric constant of a dielectric layer. For example, ifwater, which has a dielectric constant (k) of about 78, is absorbed bythe mesoporous oxide layer, then the low dielectric constant propertiesof the mesoporous oxide layer can be unintentionally altered.

In general, moisture in a porous dielectric layer can be generatedduring formation of the porous dielectric layer and can remain withinthe pores of the layer. The moisture can diffuse to the surface of anadjacent conductive metal layer and can increase its resistivity.Accordingly, it is desirable to remove moisture from porous dielectriclayers such as mesoporous oxide layers. Porous dielectric layers such asmesoporous oxide layers may be annealed to remove moisture. However, itis more desirable to deposit a capping layer on the porous layer and/ormake the porous layer hydrophobic. By doing so, additional moisture isinhibited from entering the pores of the porous layer. In addition toserving as a moisture barrier, the capping layer may also serve as anetch stop layer or a hard mask during the fabrication of an interconnectstructure.

A method of forming mesoporous oxide layers and capping layers onsubstrates using an apparatus embodiment can be described with referenceto FIG. 2. Referring to FIG. 2, substrate cassettes 106 containingsubstrates are coupled to the front staging area 102. The substratehandlers 104 index the substrates in each substrate cassette 106. Onceindexed, the substrate handlers 104 transfer the substrates to thecooling chamber 111.

The substrate handler 112 retrieves substrates from the cooling chamber110 and transfers the substrates to the spin coating chambers 114. Inthe spin-coating chambers 114, sol-gel layers are deposited on thesubstrates using spin coating processes. Alternatively, the sol-gellayers can be formed using spray coating processes (e.g., ultrasonicspray coating).

The sol-gel solution used to form the sol-gel layer can contain amixture comprising silicon/oxygen compounds, water, and a surfactant inan organic solvent. An exemplary sol-gel solution may be a mixture oftetraethylorthosilicate (TEOS), ethanol, water, and a polyethylene oxidesurfactant. An optional acid or base catalyst may be further used in theformation of the sol-gel solution.

The silicon/oxygen compounds in the sol-gel solution are thoseconventionally used in the deposition of silicon containing layers insemiconductor manufacturing. Examples of silicon/oxygen compoundsinclude silica, tetraethoxysilane (TEOS), phenyltriethyloxy silane,methyltriethoxy silane, etc.

Surfactants are used to disperse the silicon/oxygen compounds in sol-gelsolutions so that the concentration of materials in the formed sol-gellayer are uniform. The surfactants may be anionic, cationic, ornon-ionic. Non-ionic surfactants have chemical functional groups thatare uncharged or neutral hydrophilic groups while anionic and cationicsurfactants have functional groups respectfully charged negatively andpositively. Examples of suitable surfactants include primary amines,polyoxyethylene oxides, ethylene glycol ethers, etc.

Any suitable solvent may be used in the sol-gel solution. Examples ofsuitable solvents include organic solvents. Organic solvents can bealcohols such as ethanol, n-propanol, iso-propanol, n-butanol,sec-butanol, tert-butanol, ethylene glycol, etc.

Once the sol-gel solution has been deposited on the substrates, thesubstrate handler 112 retrieves the substrates and transfers thesubstrates to the curing chamber 116. The sol-gel layers on thesubstrates are then cured to remove solvent and water from the layers.During the curing step, organic solvent in the layer evaporates andmoisture in the layer is removed. This increases the concentration ofnon-volatile surfactant and silicon/oxygen compounds in the layer. Insome embodiments, the curing process may take place between about 50° C.and about 450° C. and may be performed for about one to ten minutes. Thecured sol-gel layer for each substrate has interconnecting pores ofuniform diameter.

Due to the length of curing process as compared to other processes, alarger number of curing chambers 116 can be coupled to the transferchamber 108. For example, there may be eight curing chambers per twodual substrate spin coating chambers 114. The substrate handler 112 maybe programmed to fill up the curing chambers 116 with spin-on depositedsubstrates prior to processing or may be programmed to load and unloadsubstrates in the curing chamber 116 as desired.

After curing, the substrates can be transferred to a substratestripping/annealing chamber 118. Annealing can be performed in thechamber 118 to remove surfactant from the cured sol-gel layer and toform a mesoporous oxide layer. For a high temperature non-reactive gasanneal, the stripping/annealing chamber 118 can be maintained at or nearatmospheric pressure. The oxygen concentration inside thestripping/annealing chamber 118 can be controlled to less than about 100ppm during annealing. In some embodiments, annealing can take placebetween about 200° C. and about 450° C. and for between about 30 secondsand about 30 minutes. In a typical rapid thermal annealing process, thetemperature of the substrate can increase at a rate of at least 50° C.per second.

The cured sol-gel layer may also be exposed to an oxidizing environmentto remove surfactant from the layer and to transform it into amesoporous oxide layer. In a typical oxidation stripping process, thestripping/annealing chamber 118 can be maintained at about a pressurefrom about 1 Torr to about 10 Torr. The cured sol-gel layer can beexposed to an oxidizing gas comprising, for example, oxygen, ozone, oroxygen ions at high temperatures. The oxidizing gas flow into thestripper/annealing chamber 118 can be maintained at a high flow rate(e.g., greater than 20 liters/min) to thoroughly expose the layer to thegas. In some embodiments, the substrate may be heated to between about200° C. to about 450° C. for between about 30 seconds and 30 minutesduring stripping.

In some embodiments, the oxidizing gas used in the stripping process maycomprise oxygen ions. The oxygen ions may be formed in a plasma chamberusing an RF generator or a microwave generator to form a remote plasma.The formed oxygen ions pass downstream of the plasma chamber into thestripping chamber. In the stripping chamber, the oxygen ions react withany surfactant and solvent in the layer to remove them from the layer.In some embodiments, if oxygen ions are used in the stripping process,the substrate can be exposed to the process gas for about 0.5 minutes toabout 5 minutes to remove the surfactant.

The formed mesoporous oxide layer is highly porous, and may have aporosity of greater than 50%. It may also have a dielectric constant ofless than 2.5. For example, the mesoporous oxide layer may have adielectric constant of about 1.6 to about 2.2.

Optionally, the mesoporous oxide layer may be silylated in thesilylation chamber 123. As noted above, the mesoporous oxide layer maybe rendered hydrophobic by using a silylation process.

After completing any stripping, annealing, or silylation processes, thesubstrate handler 112 retrieves the substrates from thestripping/annealing chamber 118 or the silylation chamber 123. Thesubstrate handler 112 in the first process module 101 may then directlyor indirectly transfer the substrates to the substrate handler 127 inthe second process module 210. The substrate handler 127 in the secondprocess module 210 then places the substrates in the APCVD chambers 202.

In the APVCD chambers 202, capping layers can then be deposited over themesoporous oxide layers on the substrates. For example, reactant gasesfor plasma enhanced APCVD processes may be fed to one of the plasmachambers 201. When the gases are in the plasma chamber 201, ionizingenergy may be applied to the gases to form a plasma. The ions from theplasma pass downstream of the plasma chamber 201 to the processingchamber 202. Once the ionized process gases are in the processingchamber 202, they contact the surfaces of the substrates and react onthe surfaces to form layers of material on the substrates. Thesubstrates may be moving during the deposition process to improve thethickness uniformity of the deposited layers. Capping layers are thenformed on the mesoporous oxide layers on the substrates. The processingchamber 202 is at or near atmospheric pressure during the depositionprocess.

In other embodiments, a plasma need not be formed in the APCVD process.Illustratively, a silicon nitride capping layer can be formed on amesoporous oxide layer without forming a plasma. The silicon nitridecapping layer may be formed using silane and ammonia process gases.These gases can be introduced to a processing chamber and can react atthe surface of the mesoporous oxide layer on the substrate in thechamber. The substrate temperature may be at about 700 to about 900° C.during deposition. A silicon nitride capping layer is subsequentlyformed on the mesoporous oxide layer. In this embodiment, the reactantgases need not be ionized to form the capping layer on the substrate.During the deposition process, the chamber may contain inert gases andmay be at or near atmospheric pressure.

Although mesoporous oxide layer and capping layers are described indetail above, it is understood that embodiments of the invention are notlimited to the formation of such layers on a substrate. Embodiments ofthe invention can be used to form any suitable combination of layers ona substrate.

The terms and expressions which have been employed herein are used asterms of description and not of limitation, and there is no intention inthe use of such terms and expressions of excluding equivalents of thefeatures shown and described, or portions thereof, it being recognizedthat various modifications are possible within the scope of theinvention claimed. Moreover, any one or more features of any embodimentof the invention may be combined with any one or more other features ofany other embodiment of the invention, without departing from the scopeof the invention.

1-15. (canceled)
 16. A method for processing a substrate using asubstrate processing apparatus, the method comprising: (a) depositing afirst layer on a substrate at atmospheric pressure at a firstatmospheric deposition station; (b) transferring the substrate to anatmospheric vapor deposition chamber at a second atmospheric depositionstation using a substrate transfer system; and (c) depositing a secondlayer on the substrate at atmospheric pressure within the atmosphericvapor deposition chamber at atmospheric pressure.
 17. The method ofclaim 16 wherein the substrate is a semiconductor substrate.
 18. Themethod of claim 16 wherein the first atmospheric deposition stationcomprises a spin coating chamber.
 19. The method of claim 16 furthercomprising: forming a porous dielectric layer from the deposited firstlayer, and wherein depositing the second layer on the substratecomprises depositing the second layer on the porous dielectric layer.20. The method of claim 19 wherein the porous layer and the cap layercomprise dielectric materials.
 21. The method of claim 16 furthercomprising: curing the first layer at a curing station.
 22. The methodof claim 16 wherein the atmospheric vapor deposition chamber is anatmospheric chemical vapor deposition (APCVD) chamber.
 23. The method ofclaim 16 wherein depositing the first layer comprises depositing aliquid on the substrate.